Near-field microscopy is a known technique for displaying the surface topography of a sample, such as a semiconductor material.
Near-field microscopy is based on the interactions between the sample and a probe-forming tip which scans the surface of a sample line by line.
There are various techniques of near-field microscopy based on different types of physical interactions between the tip and the sample on the one hand, and on different modes of scanning on the other.
Atomic force microscopy (or “AFM”) is an example of near-field microscopy.
In an atomic force microscope, the probe-forming tip is arranged at the free end of an elastic microcantilever. This microcantilever is capable of moving in all directions of space thanks to a piezoelectric tube with which it is associated.
The deformations (flexure/torsion) of the microcantilever due to the interaction (attraction or repulsion) between the probe-forming tip and the sample are measured by optical means.
These measurements make it possible both to reconstruct the whole course of the probe-forming tip and to measure the interaction forces between said probe-forming tip and the sample. In order to have a calibrated measurement of these forces, it is necessary to estimate the stiffness of the microcantilever.
The interaction forces are representative of characteristics of the sample such as its hardness, or its electrical conductivity or its topography or its elasticity.
When measuring deformations, the optical means also record a parasitic signal non-specific to the interactions between the probe-forming tip and the outside environment. This parasitic signal called “measurement noise” may disrupt the analysis.
In order to increase the ability of a probe-forming tip to detect low intensity interactions, it is necessary to reduce this measurement noise.
One object of the present invention is to provide a method and a system for processing signals recorded by the optical means of a near-field microscope for improving the sensitivity of the microscope by reducing the effects of measurement noise. More precisely, one object of the present invention is to provide a method and a system for estimating a stiffness of a deformable part of a system for analyzing at least one characteristic of a sample.